Failed Smog Check
 

I just failed my 3rd CA smog check yesterday and I am rather lost. I changed my O2 sensor, spark plugs, wireset, air filter and put in a new catalytic converter. However, $500 later I am still running high in hydrocarbons. My NO was bad but the new converter fixed that. Everything else is great. For my three tests my HCs were 115, 128 and 122 with a max of 108 and average 31. I have a 1989 BMW 325i.

Did you change the oil before you got tested? I always do and it always passes. You have done most everything else. Know anybody with an exhaust gas analyzer? Can run some test at home before the wasted trip.

Have you checked for vacuum leaks? The oil change is a "known thing" to help with emissions in BMWs, Porsches, etc... b/c I think the HCs build up in the old oil. If your motor is a little "tired" you are burning a little oil ... hence more HCs. Try it.

Jason

I agree here, changing the oil can help in situations like this... You'll also want to check that your vacuum hoses are in good shape as well....

I will definitly change the oil thats something I've seen alot online. Should I try high milage oils? or perhaps some seperate oil additives? I got 196K on my car.

I would just use regualr Castrol...